Waterlogging on greens is often directly linked to drainage. However, the solution does not always lie in draining water more quickly. According to Ruud de Deugd of VGR Equipment, it is at least as important to consider how water penetrates the soil and moves through the soil profile. After all, not every golf green has a drainage system. On such greens, the soil must have sufficient capacity to temporarily store rainfall. The greater the soil’s water-retention capacity, the less likely it is that rainwater will remain on the surface.
In practice, a problem arises when the soil becomes compacted. The storage capacity then decreases and rainwater cannot infiltrate the soil quickly enough. The top layer becomes saturated, resulting in puddles forming. It is striking that, deeper down in the soil profile, there is often still sufficient space available to store water. According to De Deugd, it is therefore important not to focus solely on water drainage. Improving vertical water movement deserves at least as much attention. When water can move more quickly to deeper soil layers, the available soil volume is utilised more effectively.
Sand injection
One technique that addresses this issue is sand injection. This involves injecting wet sand into the soil under high water pressure. This creates vertical columns of sand that act as vertical drains. These sand columns help water and air to move through the root zone more quickly. On greens fitted with a drainage system, the vertical drains ensure that rainwater reaches the underlying drainage pipes more quickly. This improves drainage from the green. On greens without drainage, the sand columns fulfil a different role. There, they primarily increase the rate at which rainwater infiltrates the soil. As a result, water reaches deeper soil layers more quickly, enabling the entire soil profile to function more effectively as a temporary water buffer. The upper root zone dries out more quickly, whilst the stored water can later become available to the grass plant again.
Improved water management is not the only benefit of this approach. The vertical sand columns also help to improve oxygen supply to the root zone. This can encourage deeper root growth and contribute to a healthier turf. For greenkeepers, this means that improving soil structure can serve several purposes at once: better infiltration, better aeration and more effective utilisation of available water storage capacity. De Deugd emphasises that traditional aeration methods remain an important part of maintenance. At the same time, the pores created by these methods can close again relatively quickly due to natural settlement and intensive use. With sand injection, sand-filled vertical drains remain within the soil profile. This creates a more durable connection between the ground level and the underlying soil layers. Furthermore, disruption to the playing surface is kept to a minimum. This makes it possible to carry out the treatment more frequently during the season, without any long-term impact on playability. According to De Deugd, this enables greenkeepers to adopt a more preventative rather than reactive approach to maintenance. ‘Instead of only taking action once waterlogging becomes visible, the soil structure can be maintained throughout the season.’
VGR Equipment applies this technique using the TopChanger XP. The machine injects wet sand into the root zone under high water pressure, thereby creating vertical sand drains. The technique is intended to complement existing maintenance measures. It can be used on greens with drainage, but also at sites where the focus is specifically on increasing water retention capacity. According to De Deugd, which approach is ultimately most suitable depends on various factors. ‘Among other things, the soil structure, the amount of organic matter, the presence of a thatch layer and the condition of the existing drainage system play an important role.’ His advice to greenkeepers is therefore not to focus exclusively on water drainage. ‘A healthy green starts with healthy soil. By also paying attention to infiltration, aeration and water storage in the root zone, golf courses can better prepare for more extreme weather conditions, whilst maintaining playing quality throughout the season.’
Article by Wijnand Meijboom (Greenkeeper - NWST)
